Capturing and concentrating solar energy is a well-researched subject, which has been developed and applied in the state of the art. The current challenges facing solar plants include maximising the C/Cmax. ratio of the concentrator collectors, where C is the concentration and Cmax. the maximum theoretical technical concentration, reducing geometric losses due to the so-called cosine effect, as a result of shade and obstacles between trackers, reducing optical and thermal losses and reducing installation costs to levels which will make the technology competitive in respect of other energy sources.
Maximising concentration enables thermal losses to be reduced at the plant, reducing the costs of receiver devices, typically thermosolar and photovoltaic types, in addition to increasing typical working temperatures of the heat transferring fluids or the reactors in order to obtain solar fuels.
Another considerable challenge facing the industry is the transformation of solar energy into electricity. There are two main methods employed in the state of the art in order to achieve this, namely, photovoltaic and thermosolar technologies.
Photovoltaic technology is continuously developing, and has sufficient potential for improvement to be capable of surpassing thermoelectric plants in terms of efficiency, due to the future use of advanced materials. However, it has the disadvantage of not being manageable and that there is a wavelength range above which photovoltaic cells are unable to convert all the energy from the photons into electrical power, and below which the excess energy transported by the photon is lost in the form of heat.
Thermosolar technology does not have the drawbacks of photovoltaic energy, however it presents other problems. Currently there are plans to improve tower type central receiver plants in the midterm, with respect to cost and efficiency compared to the other commercial technologies in the large scale electricity power plant market. Nevertheless, central receiver plants have high cosine effects (effect of reduction in the reflective surface area, which causes the incident beams to form a specific angle with the normal angle to the surface) overflows in the receiver, losses through transmission and other phenomena which make it less efficient when compared to the potential of photovoltaic technology. In terms of distributed generation, or market of dozens of kW, Stirling discs are a promising yet still expensive development solution. One of the issues which makes this technology so expensive is the fact of having to support a heavy cantilevered engine in the concentrator focus.
Thermosolar technology has the advantage of thermal inertia and the possibility of storing transformed energy along with the possibility of hybridisation.
The limitations of thermosolar plants can be offset by using light guides to transport concentrated light. It is known in the art that light guides permit numerical openings that is, the range of angles for which the guide accepts light, are very high, the disadvantage is that that they are manufactured using materials which are unable to transmit all the spectral width of the sun, leading to losses, thus this technology is not viable. The solar spectrum window which can be guided without losses ranges from 1250 nm to a limit exceeding 1650 nm presenting losses of 0.2 dB/km at around 1550 nm.
Solar lasers which partially transform the incident spectrum of solar light into a laser beam are also known in the art. This type of solar laser consists of the following:                An optical cavity, also known as resonator or oscillator, consisting of two reflective mirrors between which the laser light is trapped as it is alternatively reflected in both;        A doped active medium situated between both reflecting mirrors, which may be solid, liquid or gaseous, the function of which is to amplify a range of wavelengths and specific modes so that the photons suffer multiple reflections within the cavity and pass through it;        A source of solar light, able to generate population inversion in the active medium, that is, light able to ensure that in said medium there are more atoms in an excited state or of the highest quantum mechanical energy, which will enable the greater part of the system atoms to emit light in what is known as stimulated conditions.        
Both the resonator and the active medium of the solar laser are preferably cylindrical and the reflecting mirrors are situated at their ends. Solar lasers are normally illuminated laterally by concentrated solar light using CPC or Compound Parabolic Concentrator type concentrators. The first reflecting mirror of the cavity is adapted to be highly reflective only in the area of the laser outlet length and its surroundings. The second mirror, that is, that of the laser outlet partially reflects incident laser light and transmits the fraction which is not reflected, this transmitted light is in itself the laser light that generates the device. In this way photons are trapped in the resonator moving from one mirror to another and amplified by the active medium.
If the amplification is high enough to overcome losses, a phenomenon commonly known as threshold condition, a single photon may be amplified by various orders of magnitude, thus producing a considerable number of coherent photons trapped within the resonator. If the photons come and go between the mirrors for a sufficiently long period of time, the laser will achieve a permanent regime and a constant power will circulate between the mirrors. The solar laser may therefore transform part of the entering solar spectrum into an outgoing laser beam at a specific wave length. The active medium material has an absorption spectrum which does not necessarily need to coincide with its emission spectrum.
Solar energy may be pumped to the laser either through the lateral face or longitudinally, that is, through one of its ends, so that the light is injected in the direction of the laser beam generated.
PCF (Photonic Crystal Fibre) guides are also known in the state of the art and are a type of optic fibre based on the properties of photonic crystals and they normally have a nucleus and a coating with a different refraction index so that light may be transported considerable distances through them, either through a single mode nucleus or in the interior of the nucleus-coating interface due to the total internal reflection mechanism based on the light guide, caused by a difference in the refraction index between the two media.